It is common practice when operating a self-propelled harvester in its active harvesting or cropping mode, particularly a sugar cane harvester, to operate the engine continuously at a high speed, including its highest speed, to ensure sufficient power and run crop equipments at highest speed. This practice fails to accurately match the engine speed to power demand, which is inefficient and results in less than optimal fuel economy.
On a harvester, engine power, measurable as torque, is commonly distributed amongst numerous systems, particularly, the propulsion system, the harvesting and processing systems, and on a sugar cane harvester, to a chassis height adjustment system that compensates for uneven terrain on a continuous basis during active harvesting. The harvesting and processing systems of a harvester typically include conveyors and choppers that utilize a significant amount of engine torque, but which utilization will vary as a function of several factors, namely, crop density or yield, and cane variety. Occasionally during active harvesting operation, cut crop material will choke or clog elements of the above systems, requiring steps to remove or expel the material causing the choking condition.
At other times, operation of the harvester will require substantially less power. For instance, during stationary idling, and travel with the base cutter or cutters or other harvesting apparatus raised and out of contact with the crop. At these times, operation of the engine at a lower speed is typically more efficient.
Many harvesters include an engine control system operable for managing the engine responsive to harvesting apparatus and conditions to achieve better power management and efficiency. Reference generally, Heisey, U.S. Pat. No. 6,865,870, issued Mar. 15, 2005 to CNH America LLC, which provides a system that provides different overall power levels for different operating modes, e.g., field work verses road travel. There are also known systems that set power levels as a function of equipment connected to the harvester. Several such systems utilize detectors for determining the identity of a header attached to a combine harvester, and provide corresponding stored engine power curves for the particular headers. Reference in this regard, Ehrecke, U.S. Pat. No. 6,397,571, issued Jun. 4, 2002 to Deere and Company. Manufacturers have also devised engine power management schemes for setting available engine power levels as a function of systems of the machine that are currently engaged or operating, e.g., straw chopper, propulsion system, harvester assembly, separator, as indicated by the positions of switches for engaging or activating the respective systems, e.g., the on/off switches for the systems. Reference in this regard, Wyffels, U.S. Pat. No. 5,878,557, issued Mar. 9, 1999 to Deere and Company. Still other engine management schemes rely on sensed measurements of actual power usage of the various systems, for determining available power level values. Reference in this regard, Dickhaus, U.S. Pat. No. 6,073,428, issued Jun. 13, 2000 to Claas Selbstfahrende Erntemaschinen GmbH.
However, an observed shortcoming of setting maximum available power as a function of overall operating mode as suggested above in the first patent, and based on header identity alone, such as proposed in U.S. Pat. No. 6,397,571, is that too much available power may be present in instances when the harvesting and other systems require less power, e.g., crop density or yields are lower, or systems or subsystems are disengaged for a period or intermittently. In this latter instance, removing the power requirements of one or more of the major systems, i.e., turning off or disengaging some of the systems, the balance of subsystems still on or engaged can divide the total available power. In many cases, however, this can result in inefficiency, as the engine is providing more power than is actually necessary for current operating demand.
Setting maximum available power based on the identity of engaged or activated subsystems such as by monitoring on/off switches as proposed in U.S. Pat. No. 5,878,557, also suffers from a shortcoming that it will necessitate setting the available power level to accommodate the maximum expected power usage of those subsystems, and doesn't accommodate reduced power needs of different configurations of the subsystems, and when power demand is temporarily reduced or increased due to changes in crop density, etc.
Setting maximum available power as a function of measured actual usage, as proposed in U.S. Pat. No. 6,073,428, suffers from the shortcoming that the actual power usage can vary significantly during operation as a result of temporary or intermittent operating conditions, again, such as passage through areas of greater or lesser crop density, and passage of slugs of crop material through the crop processing systems, such that the level of available power will be correspondingly varied, reactive to demand, as opposed to in anticipation of demand, which can be problematic. For example, if the actual power usage during an interval of time is relatively low as a result of smooth operating conditions, the available maximum engine power may be set to reflect this. But, when an increase in power demand occurs, the additional engine power available may be inadequate. Then, if in response the system automatically or the operator manually increases power, after the need for the additional power has passed, the now available power may be too great, which is inefficient.
Thus, what is sought is a manner of power management that efficiently delivers necessary power to systems and subsystems of a harvester in a responsive and efficient manner, particularly when actively harvesting, and adaptable to the power demands of a sugar cane harvester.